1. Field of the Invention
This invention relates in general to packoff assemblies located between a casing hanger and a wellhead, and in particular to a packoff assembly for a subsea well employing metal seals.
2. Description of the Prior Art
In a conventional subsea well, a wellhead will be located on the sea floor. Riser pipe will extend from the wellhead to a floating vessel on the surface. When running casing, a casing hanger is connected to the upper end of the casing string and landed on a shoulder in the wellhead. The casing hanger is lowered on a running tool.
After cementing, a packoff is positioned in the annular space between the casing hanger and the wellhead. The packoff may be carried by the running tool or lowered in a separate trip. There are a number of different types of packoffs in use and described in various patents. Some employ elastomeric seals, others metal seals, and others a combination of both.